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Finals Exam General Chemistry > Unit 3 – The Chemistry of Engineering Materials Polymers > Flashcards

Unit 3 – The Chemistry of Engineering Materials Polymers Flashcards

1
Q

Bold

A ___________ is a molecular compound that can be distinguished by a high molar mass, ranging into thousands and even millions of mass and they are made up of many repeating
units.

A

polymer

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2
Q

_____________ were first developed in the early 20th century, and these polymers remarkably transformed our world as different materials can be created with properties that are ideal for different applications.

A

Synthetic (man-made) polymers

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3
Q

Polymers that have been around
since life itself began.

A

Natural Polymers

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4
Q

Cellulose, starch, and other complex carbohydrates are examples of

A

Natural Polymers

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5
Q

It is a polymer obtained from rubber trees and even the code
for life itself, DNA, is a natural polymer.

A

Natural rubber

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6
Q

Fill in the blanks

Because of the _________, we might expect that molecules containing thousands of carbon and hydrogen atoms can form a massive number of structural and geometric
isomers (if C=C bonds are present).

A

size polymers

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7
Q

Bold

___________are the small molecules that are used for synthesizing polymers and each of it is analogous
to a link in a chain.

A

monomers

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8
Q

Monomers (_____ meaning “one”; _____ meaning “unit”)

A

mono
meros

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9
Q

Monomers ( mono meaning “____”; meros meaning “______”)

A

one
unit

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10
Q

Bold

They can be created from one monomer, of from
a combination of two or more different monomers.

A

polymers

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11
Q

Bold

If a polymer is made up of only type of monomer (e.g. polyethylene), then it is known as __________.

A

homopolymer

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12
Q

Give three homopolymers that are synthesized by the radical mechanism

A

Teflon TM
polytetrafuoroethylene
poly(vinyl chloride) (PVC)

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13
Q

___________ can be made from many different starting materials which usually come from crude oil (raw material).

A

Synthetic polymers

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14
Q

___________ is the starting material for many
plastics, pharmaceuticals, fabrics, and other carbon-based products.

A

crude oil

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15
Q

Bold

The molecules in polymers are gigantic and because of their size they are often referred to as __________.

A

macromolecules

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16
Q

The backbone of each of a carbon-chain polymer is a string
of carbon atoms and within each molecule, the atoms are bound together by___________ bonds.

A

covalent interatomic

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17
Q

Each of the two remaining valence electrons for every carbon atom may be involved in side bonding with atoms or radicals that are positioned adjacent to the chain. Of course,
both _____and __________ are also possible.

A

chain
side double bonds

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18
Q

is a gas at ambient temperature and pressure which
has the following molecular structure.

A

hydrocarbon ethylene (C2H4)

page 126 for figure

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19
Q

Under appropriate conditions, ethylene gas reacted and it will transform to ___________ which is a solid polymeric material.

A

polyethylene (PE)

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20
Q

It is a solid polymeric material.

A

polyethylene (PE)

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21
Q

transforming ethylene to polyethylene

This process begins when an active center is formed by the reaction between an __________ (R·) and the ethylene monomer.

A

initiator or catalyst species

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22
Q

Next, the polymer chain forms by the __________ of monomer units to this actively growing chain molecule

A

sequential addition

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23
Q

Other chemistry of polymer structure such as tetrafluoroethylene monomer to form
__________________ (PTFE)

A

polytetrafluoroethylene

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24
Q

Italicize

Polytetrafluoroethylene (having the trade name Teflon) belongs to a family of polymers called the _____________.

A

fluorocarbons

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25
Q

The ______________(CH2=CHCl) is a slight variant of that for ethylene, in which one of the four H atoms is replaced with a Cl atom.

A

vinyl chloride monomer

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26
Q

vinyl chloride monomer leads to ____________

A

poly (vinyl chloride)

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27
Q

enumerate the polymer structures

A

Linear
Branched
Crosslinked
Network

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28
Q

are those in which the repeat units are joined together end to end in single chains.

A

Linear Polymers

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29
Q

-These long chains are flexible where each circle
represents a unit.

A

linear

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30
Q

-There may be extensive van der Waals and
hydrogen bonding between the chains.

A

Linear

31
Q

-Some of the common polymers that form with
________ structures are polyethylene, poly(vinyl
chloride), polystyrene, poly(methyl methacrylate),
nylon, and the fluorocarbons.

A

linear

32
Q

-The chain packing efficiency is reduced with the
formation of side branches, which results in a
lowering of the polymer density.

A

Branched

33
Q

-For example, high-density polyethylene (HDPE) is
primarily a linear polymer, whereas low-density
polyethylene (LDPE) contains short-chain
branches.

A

Branched

34
Q

-Adjacent linear chains are joined one to another at various positions by covalent bonds.

A

crosslinked

35
Q

-The process of __________ is achieved either
during synthesis or by a nonreversible chemical
reaction.

A

crosslinking

36
Q
A
37
Q
A
38
Q

is accomplished by
additive atoms or molecules that are covalently
bonded to the chains.

A

crosslinked

39
Q

-Many of the rubber elastic materials are
________.

A

crosslinked

40
Q

-These are multifunctional monomers forming three or more active covalent bonds make three-
dimensional networks.

A

Network

41
Q

-A polymer that is highly crosslinked may also be
classified as a _______ polymer.

A

network

42
Q

-These materials have distinctive mechanical and
thermal properties; the epoxies, polyurethanes,
and phenol-formaldehyde belong to this group.

A

network

43
Q

Presently, there are more than ___________ synthetic polymers known,

A

60,000

44
Q
A
45
Q

six types of polymers

A

polyethylene LDPE (4)
polyethylene HDPE (2)
polyvinyl chloride PVC or V (3)
polystyrene PS (6)
polypropylene PP (5)
polyethylene terephthalate PETE or PET (1)

46
Q

-Translucent if not
pigmented.
-Soft and flexible.
-Unreactive to acids
and bases.
-Strong and tough.

A

polyethylene LDPE

47
Q

Bags, films, sheets,
bubble wrap, toys,
wire insulation.

A

polyethylene LDPE

48
Q

-Similar to LDPE
-More rigid, tougher,
slightly more dense.

A

polyethylene HDPE

49
Q

Opaque milk, juice,
detergents, and
shampoo bottles.
Buckets, crates, and
fencing

A

polyethylene HDPE

50
Q

-Variable. Rigid if
not softened with a
plasticizer. Clear
and shiny, but often
pigmented.
Resistant to most chemicals, including
oils, acids, and
bases.

A

polyvinyl chloride

51
Q

Rigid: Plumbing
pipe, house siding,
charge cards, hotel
room keys.
Softened: Garden
hoses, waterproof boots, shower
curtains, IV tubing.

A

polyvinyl chloride

52
Q

-Variable. “Crystal”
form transparent,
sparkling,
somewhat brittle.
-“Expandable” form
lightweight foam.
-Both forms rigid
and degraded in
many organic
solvents.

A

polystyrene

53
Q

“Crystal” form: Food
wrap, CD cases,
transparent cups.
“Expandable” form:
Foam cups,
insulated
containers, food
packaging trays, egg
cartons, packaging
peanuts.

A

polystyrene

54
Q

-Opaque, very
tough, good
weatherability. High
melting point.
-Resistant to oils.

A

polypropylene

55
Q

Bottle caps. Yogurt,
cream, and
margarine
containers.
Carpeting, casual
furniture, luggage.

A

polypropylene

56
Q

-Transparent,

strong, shatter-
resistant. -

Impervious to acids
and atmospheric
gases.
-Most costly of the
six.

A

Polyethylene
terephthalate

57
Q

Soft-drink bottles,
clear food
containers,
beverage glasses,
fleece fabrics, carpet
yarns, fiber-fill
insulation.

A

Polyethylene
terephthalate

58
Q

_______________ is an alternative way of expressing average chain size of a polymer.

A

Degree of Polymerization (DP)

59
Q

The ______________ is obtained by dividing the chains into a series of size ranges and then determining the number fraction of chains within each size range

A

number-average
molecular weight Mn

60
Q

A ____________is based on the weight fraction of molecules within the various size ranges.

A

weight-average molecular weight Mw

61
Q

two subdivision of polymers

A

thermoplastics
thermosets

62
Q

they soften upon heating and later liquefy, then it hardens when cooled.
This process is reversible and can be repeated.

A

thermoplastics

63
Q

Examples of common ____________________ polymers are polyethylene, polystyrene,
poly(ethylene terephthalate), and poly(vinyl chloride).

A

thermoplastic

64
Q

For ________________ polymers which are network polymers, they do not soften upon
heating and they become permanently hard during their formation.

A

thermosetting

65
Q

Examples of these _______________ (crosslinked and
network polymers) are vulcanized rubbers, epoxies, phenolics, and some polyester resins.

A

thermosets

66
Q

bold

A ___________ is composed of two repeat units

A

copolymer

67
Q

____________ are usually copolymers.

A

Synthetic
rubbers

68
Q

4 copolymer arrangement

A

Random
Alternating
Block
Graft

69
Q

two different units are randomly dispersed along the chain

A

Random

70
Q

two repeat units alternate chain positions

A

alternating

70
Q

identical repeat units are clustered in

blocks along the chain

A

block

71
Q

homopolymer side branches of one type
may be grafted to homopolymer main
chains that are composed of a different
repeat unit

A

graft

72
Q

In ___________, the atomic arrangement in polymer materials are more complex
as compared to metals and ceramics because in polymers it involves molecules instead of
just atoms or ions.

A

crystalline state

73
Q

____________ is the packing of molecular chains to produce an ordered atomic array.

A

Polymer crystallinity

Finals Exam General Chemistry (3 decks)

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